Table 1.

Demographic information of the subjects from the ADHD-200 sample.

Group	N	Males	Mean age (SD) – years
TD controls	546	286 (52.4%)	12.29 (3.46)
Combined	249	193 (77.5%)	11.21 (3.02)
Inattentive	122	93 (76.2%)	12.16 (3.00)
Hyper/impulsive	12	10 (83.0%)	12.49 (4.62)
Whole ADHD sample	383	296 (77.3%)	11.56 (2.99)

TD, typically developing. Although the two-sample t-tests comparing TD controls vs. ADHD (p = 0.001) and combined vs. inattentive (p = 0.003) indicate statistical differences in age, these differences were not relevant for classification (total scores of a logistic regression based solely on age are 0.50 and 0.49, respectively, i.e., very close to the scores by chance).